(l) The tax for each year payable under any of the provistons of this Act may be assessed, levied and collected 1n advance dunng the year m monthly or other prescribed imtalments, and for that purpose a dealer may be required to furmsh withm the prescnbed penod either an advance esumate of his turnover fot the year, ot such penod1cal returns of the actual tllrnover as may be prescnbed. The assessing authority may determme the amount of - tax payable m respect of any penod and on such assessment the dealer shall pay the sum demanded within such t1me as may be fixed by such authority.
(2) If no return is submttted by the dealer under sub-section ( i) within the prescnbed period, or if the return submitted by him appears to the assessing authonty to be incorrect or incomplete, the assessing authonty may dete;mme the amount of tax payable by the dealer m accordance w1th the pmvis10ns ofsub-sectJOn (3) of section 17.
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(3) If the assessing authority has reason to believe that the provisional asses>ment made by it for any period was based on too low a turnover 01 was made at too low a rate or was based on too h1gh a turnover or was made at too high a rate, it may enhance or reduce, as the case may be, such proviswnal assessment:
Provided that before making an enhancement of the provisional assessment as aforesa1d, the assessmg authority ~hall, except where such f'nhancement 1s based on the turnover finally determmcd for the prece ding year, g1ve a Ieasonable opportunity to the dealer to show cause agamst such enhancement and make such enquiry as 1t may consider n eccssa 1 y.
( 4) The assessment, levy and collectron of tax under this 'ection shall be subject to such adjustment as may be prescribed on the com pletion of final assessment in the manner prescribed.